A number of safety devices for use in vehicles to protect vehicle occupants in the event of a collision are known and well documented in prior art. The most widely excepted and used are seat belts or shoulder belts which have saved many lives principally by keeping the occupants from being thrown about inside the vehicle or being thrown out of the vehicle, however, the typical seat belt does not protect the driver from coming into contact with the steering wheel.
In recent years apparatus has been developed which upon pressurized activation is propelled towards an occupant of the vehicle to prevent the occupant from striking the structure of the vehicle in the event of a collision such as the well known air bag protection device U.S. Pat. No. 3,799,576. The typical air bag apparatus comprises an inflatable, elastic container having little or no permeability to gas which at the instant of collision is explosively filled with a gaseous mixture by means of a suitable releasing arrangement. In its rest position the air bag is placed in tightly folded condition in a suitable container in the vehicle in front of the occupant it is designed to protect. In order to perform its function the air bag must be inflated within a few fractions of a second of the initial collisional impact and inflation in such a short period of time generally causes a sound in the vehicle corresponding to the decibel levels produced by detonation of a shotgun blast. Such sound levels commonly cause damage to the eardrums of the occupants in the vehicle. Another disadvantage in the use of the air bag system is the enormous increase in volume and pressure inside the vehicle when the air bag is activated. This also affects the eardrums of the occupants of the vehicle and commonly causes damage to certain parts of the vehicle body due to the increase in pressure. The doors of the vehicle are sometimes deformed by the increased pressure so that they can no longer be opened after the accident has occurred thereby causing an additional safety hazard.
Also, the air bags are triggered by a pre-set collision speed such as 15-25 M.P.H. and does not protect the driver from collision with the steering wheel at lower speeds of impact which can still cause serious injury and discomfort.
Also, the air bag is not readily reusable as it substantially fills the space in front of the driver and must be "re-placed" by experts in the field of air bags.
Also, the typical air bag is generally a factory item which is installed at the point of manufacture and to the knowledge of the present inventors is not an "add-on" feature.
An example of such an air cushion is the apparatus of U.S. Pat. No. 4,944,529 which teaches a cushion of substantially quadrilateral configuration and includes superposed congruent impact surfaces joined to each other along their longitudinal and lateral margins, by side surfaces folded inwardly.
All of the inflatable on contact "air bags" rely on sensor means which senses a pre-determined collision impact of a pre-determined force or mechanical releases such as the device taught by patent U.S. Pat. No. 3,799,576 and the safety of the occupant depends on the reliability of many elements, any one of which may fail under actual collision conditions.
Prior art safety devices, designed to provide impact energy absorbing protection when a vehicle operator is thrown forward onto the steering wheel upon the occurrence of a collision, have been designed for impacts by the entire upper body of the operator. Such prior art safety devices have therefore been designed for impacts in which the impact area is considerably large, corresponding to the entire upper body. Such impacts occur when the upper body is not restrained.
With the increased use of vehicle safety belts, particularly those which include a belt across the upper body of the vehicle occupants, such as a shoulder belt the frequency of driver impact on the steering wheel with the chest has been considerably decreased. In a collision, however even when an operator is using a seat and shoulder belt, it is possible for his head to be thrown forward in a nodding motion and impact upon the steering wheel. Motion of the vehicle steering wheel upwards and toward the back of the vehicle upon the occurrence of a severe collision can contribute to the tendency of the driver's head to strike the hub or spoke members on steering wheels and have not been designed for impact by the head of the vehicle operator, which involves a relatively small impact surface area as compared to impact by the upper body of the driver.
No means is provided for the operator of the vehicle to test the condition of the air bag or its inflating means and this problem is addressed by the present invention.
Two separate and distinct problems exist which have been addressed by the above noted and other prior art, i.e., that of slow speed impact and that of higher speed impacts.
High speed impact apparatus have been taught by prior art reference which include multiple compartments such as patent U.S. Pat. No. 3,752,501 which provide, when inflated, a peripheral rim compartmentation in juxtaposition to the steering wheel rim and center compartmentation in overlying juxtaposition to the steering wheel hub, however, this apparatus and other simulated devices are only activated on pre-set collision impact and provide no protection at lower speed as does the apparatus disclosed by the present inventors' '137 application.
While the '137 application of the present inventors addresses the problem of low speed impact it does not address the problem of higher speed impacts.
The present invention addresses both these problems and is a unique and distinct improvement over known prior art in that it provides an air bag which is inflated on assembly and an additional air bag which is inflated on impact, both associated in one unit.